diff --git a/src/Detective/FilenameDetector.php b/src/Detective/FilenameDetector.php
new file mode 100644
index 0000000..e7ede67
--- /dev/null
+++ b/src/Detective/FilenameDetector.php
@@ -0,0 +1,45 @@
+<?php
+
+namespace IndifferentKetchup\Codex\Detective;
+
+/**
+ * Match a regex against the source path of the log file
+ *
+ * Returns a configured weight when the LogFileInterface exposes a non-null
+ * path that matches $pattern. Returns false when no path is known
+ * (StringLogFile, StreamLogFile) or when the pattern does not match. Pattern
+ * is compared against the full path; anchor with $ for strict suffix matching.
+ *
+ * @package IndifferentKetchup\Codex\Detective
+ */
+class FilenameDetector extends Detector
+{
+    protected ?string $pattern = null;
+    protected float $weight = 0.95;
+
+    public function setPattern(string $pattern): static
+    {
+        $this->pattern = $pattern;
+        return $this;
+    }
+
+    public function setWeight(float $weight): static
+    {
+        $this->weight = $weight;
+        return $this;
+    }
+
+    public function detect(): bool|float
+    {
+        $path = $this->logFile->getPath();
+        if ($path === null || $this->pattern === null) {
+            return false;
+        }
+
+        if (preg_match($this->pattern, $path) === 1) {
+            return $this->weight;
+        }
+
+        return false;
+    }
+}
diff --git a/test/tests/Detective/FilenameDetectorTest.php b/test/tests/Detective/FilenameDetectorTest.php
new file mode 100644
index 0000000..5e10e04
--- /dev/null
+++ b/test/tests/Detective/FilenameDetectorTest.php
@@ -0,0 +1,47 @@
+<?php
+
+namespace IndifferentKetchup\Codex\Test\Tests\Detective;
+
+use IndifferentKetchup\Codex\Detective\FilenameDetector;
+use IndifferentKetchup\Codex\Log\File\PathLogFile;
+use IndifferentKetchup\Codex\Log\File\StringLogFile;
+use PHPUnit\Framework\TestCase;
+
+class FilenameDetectorTest extends TestCase
+{
+    public function testReturnsWeightWhenPatternMatchesPath(): void
+    {
+        $detector = (new FilenameDetector())
+            ->setPattern('/simple\.log$/')
+            ->setWeight(0.9);
+        $detector->setLogFile(new PathLogFile(__DIR__ . "/../../data/simple.log"));
+
+        $this->assertSame(0.9, $detector->detect());
+    }
+
+    public function testReturnsFalseWhenPatternDoesNotMatch(): void
+    {
+        $detector = (new FilenameDetector())
+            ->setPattern('/notthere\.txt$/');
+        $detector->setLogFile(new PathLogFile(__DIR__ . "/../../data/simple.log"));
+
+        $this->assertFalse($detector->detect());
+    }
+
+    public function testReturnsFalseWhenLogFileHasNoPath(): void
+    {
+        $detector = (new FilenameDetector())
+            ->setPattern('/anything/');
+        $detector->setLogFile(new StringLogFile("content"));
+
+        $this->assertFalse($detector->detect());
+    }
+
+    public function testReturnsFalseWhenPatternUnset(): void
+    {
+        $detector = new FilenameDetector();
+        $detector->setLogFile(new PathLogFile(__DIR__ . "/../../data/simple.log"));
+
+        $this->assertFalse($detector->detect());
+    }
+}